ECMP/multipath support

[Joakim Tjernlund]

>
> > > > Other packets are sent to the neighbor IP address, which is a slight
> > > > diversion from RFC 2328, but should not cause any problems.
> > >
> > > But a stricter router may reject OSPF msg over an ptp links if
> > > they aren't addressed to AllSPFRouters.
> >
> > I just noticed you impl. a PTMP I/F type, nice :)
>
> I updated to new nexhp calc. patch to match your latest
> changes. I hope you like it.

Did some more spf improvements. Lets see if you like these too: